In etching contact holes having a high aspect ratio, an etch stop may occur at a higher probability as the depth of the hole bottom increases. As a method of preventing an etch stop, for example, Patent Document 1 discloses a method that involves increasing the pressure within a processing chamber according to the etching progress. According to this method, the difference between the pressure within the chamber and the pressure within the holes being formed is reduced as much as possible at each depth.